\section{Introduction}

\begin{frame}
  \frametitle{What is 'Linux User Mode' architecture}
  What we don't have:
  \begin{enumerate}
    \item GDT modification (can be skipped)
    \item access to memory by physical address
    \item page table exchanging (modification is possible)
    \item interrupts from devices (some of which is wrapped as signals)
  \end{enumerate}

  What we have: 
  \begin{enumerate}
    \item system calls
    \item user memory space
  \end{enumerate}

  Question: How to simulate what we don't have with what we have?
\end{frame}